JP2019143585A - Centrifugal pump - Google Patents

Abstract

To provide a centrifugal pump capable of suppressing intrusion of foreign matter, without impairing a high place or long distance transfer function for liquid lifting as a high lifting pump.SOLUTION: A centrifugal pump 1 has an impeller 10 rotating around a predetermined axis, and a pump casing 11 housing the impeller 10. Between an outer peripheral part 103 of the impeller 10 and an opposite part 15 of the pump casing 11 facing the outer peripheral part 103, an annular gap AG is formed. In the annular gap AG, the dimension of a gap in a radial direction of the impeller 10 continuously decreases, increases, or increases after decreasing from a front surface 10a side to a back surface 10b side in an axis direction of the impeller 10.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a centrifugal pump.

  As is well known, the centrifugal pump has a structure in which an annular gap (side clearance) formed between the inner peripheral surface of the pump casing and the outer periphery of the impeller is narrowed with an increase in head height. However, if the side clearance is made narrower in response to an increase in the head height, for example, in sewage, an impeller restraint (lock) accident due to the biting of foreign matter becomes a problem. Further, if the lateral clearance is increased in order not to cause foreign matter to be caught, the height of the pumped liquid or the long-distance transfer function as the high head pump is impaired.

  For this reason, in the centrifugal pump described in Patent Document 1 below, a narrow annular gap is held between the upper surface of the inner peripheral surface of the pump casing and the surface facing the outer peripheral surface of the shroud of the impeller. A configuration is adopted in which a screw groove that is rolled down along the rotation direction of the impeller is formed in both or one of the upper portion of the peripheral surface and the outer peripheral surface of the shroud of the impeller. By engraving such a screw groove, it is possible to form a downward flow in the annular gap and suppress foreign matter biting.

JP-A-2005-240629

  However, among centrifugal pumps, there are some centrifugal pumps whose center of the pump casing is not aligned with the center of the impeller due to the effects of parts processing accuracy and the like, and the gap size of the annular gap is not uniform. As a result, foreign matter may enter from the annular gap having a large gap size, and the foreign matter may move to the narrow gap portion of the annular gap as the impeller rotates and bite in a wedge shape. . If this foreign matter gets caught in the parallel part of the impeller and the pump casing where the screw groove is not engraved, the foreign matter will not come off naturally and the pump must be disassembled. is there.

  The present invention has been made in view of the above-mentioned problems, and is a centrifugal pump that can suppress the biting of foreign matter without impairing the height of a pumped liquid or a long-distance transfer function as a high head pump. For the purpose of provision.

  (1) A centrifugal pump according to an aspect of the present invention is a centrifugal pump having an impeller that rotates about a predetermined axis and a pump casing that houses the impeller, and an outer peripheral portion of the impeller; An annular gap is formed between the outer peripheral part and the facing part of the pump casing, and the annular gap extends in the radial direction of the impeller from the front side to the back side in the axial direction of the impeller. The gap size is continuously decreasing, increasing, or increasing after decreasing.

(2) In the centrifugal pump described in (1) above, a chamfered portion that forms the annular gap is formed on at least one of the outer peripheral portion of the impeller and the opposed portion of the pump casing. May be.
(3) In the centrifugal pump described in (2) above, the chamfered portion may be formed on at least one of the front surface side and the back surface side of the outer peripheral portion of the impeller.
(4) In the centrifugal pump described in the above (2) or (3), the chamfered portion is formed on at least one of the front surface side and the back surface side of the facing portion of the pump casing. May be.
(5) The centrifugal pump described in (2) to (4) above, wherein the chamfered portion includes one of the front surface side and the back surface side of the outer peripheral portion of the impeller, and the pump casing. It may be formed on the other side different from the one side among the front surface side and the back surface side of the facing portion.
(6) In the centrifugal pump described in the above (5), an obtuse angle portion may be formed in an outer peripheral portion of the impeller in which the chamfered portion is formed and a facing portion of the pump casing.

  According to the above aspect of the present invention, it is possible to provide a centrifugal pump capable of suppressing the biting of foreign matter without impairing the height of the pumped liquid or the long-distance transfer function as the high head pump.

It is sectional drawing of the centrifugal pump which concerns on one Embodiment. It is an arrow AA figure shown in FIG. It is a principal part expanded sectional view of the centrifugal pump which concerns on one Embodiment. It is explanatory drawing explaining the effect | action by the centrifugal pump which concerns on one Embodiment. It is a figure which shows the modification of the principal part structure of the centrifugal pump which concerns on one Embodiment. It is a figure which shows the modification of the principal part structure of the centrifugal pump which concerns on one Embodiment. It is a figure which shows the modification of the principal part structure of the centrifugal pump which concerns on one Embodiment.

  Hereinafter, a centrifugal pump according to an embodiment of the present invention will be described with reference to the drawings. In the following description, as an example of the centrifugal pump, a submersible pump for transferring a liquid in which impurities and filth are mixed, such as sewage, waste water, or river water, is exemplified. The present invention is widely applicable to centrifugal pumps in general and is not limited to the submersible pump.

FIG. 1 is a cross-sectional view of a centrifugal pump 1 according to an embodiment.
A centrifugal pump 1 shown in FIG. 1 includes a pump 2, a motor 3 attached to the upper part of the pump 2, and a rotating shaft 4 inserted vertically between the pump 2 and the motor 3.

  Hereinafter, the direction in which the axis AL of the rotating shaft 4 extends is referred to as the axial direction, the direction orthogonal to the axis AL is referred to as the radial direction, and the direction of circling around the axis AL is referred to as the circumferential direction. Further, the description will be made assuming that the pump 2 side of the rotating shaft 4 along the axis AL is the lower side and the motor 3 side of the rotating shaft 4 is the upper side.

  The pump 2 includes an impeller 10 connected to the rotating shaft 4 and a pump casing 11 that houses the impeller 10. The impeller 10 is fixed to the lower end portion of the rotary shaft 4 and rotates around the axis line AL. The pump casing 11 is formed with a pump chamber 12 that houses the impeller 10, a suction port 13 and a discharge port 14 that communicate with the pump chamber 12, and a facing portion 15 that faces the impeller 10 in the radial direction. Yes.

  The suction port 13 is formed coaxially with the axis AL at the lower part of the pump casing 11. The pump chamber 12 is formed in a scroll shape around the suction port 13. The discharge port 14 is formed so as to communicate with the outer peripheral portion of the scroll-shaped pump chamber 12. The facing portion 15 is formed on the upper portion of the pump casing 11 so as to be coaxial with the axis AL and slightly larger than the outer diameter of the impeller 10.

  The outer peripheral portion 103 of the impeller 10 faces the facing portion 15 of the pump casing 11 with a gap in the radial direction. The outer peripheral part 103 is formed by the outer peripheral side peripheral part of the shroud 101 of the impeller 10. The shroud 101 is provided with a plurality of blades 102 on the surface 10a side (suction port 13 side) of the impeller 10.

  An intermediate casing 20 is attached to the upper portion of the pump casing 11. The intermediate casing 20 is disposed on the rear surface 10b side of the impeller 10 and has an insertion hole 21 through which the rotary shaft 4 is inserted. A seal holding portion 22 is formed at the opening peripheral edge on the upper side of the insertion hole 21. The seal holding part 22 holds a mechanical seal 23.

  A lower bearing bracket 40 is attached to the upper part of the intermediate casing 20. The lower bearing bracket 40 is provided with a lower bearing 41 that supports the rotating shaft 4. The lower bearing bracket 40 is formed with a seal holding portion 42 that holds the mechanical seal 23. An oil filling plug (not shown) is provided on the side wall portion of the intermediate casing 20 so that lubricating oil can be supplied from the outside to the space S in which the mechanical seal 23 is disposed.

  The space S is formed between the bottomed cylindrical intermediate casing 20 and the top-bottomed cylindrical lower bearing bracket 40. The mechanical seal 23 is a double type, and prevents liquid from entering from the pump casing 11 side to the mechanical seal 23 side, and also prevents leakage of lubricating oil from the mechanical seal 23 side to the stator 50 and rotor 51 side described later. To do.

  A cylindrical motor frame 30 is fitted on the lower bearing bracket 40. The motor frame 30 is disposed coaxially with the axis AL, and surrounds the rotating shaft 4 extending to the outside (upward) of the pump casing 11 via the insertion hole 21. A stator 50 (stator core 50a) is fitted into the motor frame 30.

  The stator 50 has a stator core 50a fixed (for example, shrink-fitted) to the inner peripheral surface of the motor frame 30, and a stator coil 50b wound around the stator core 50a. On the other hand, a rotor 51 is attached to the rotating shaft 4. The rotor 51 has a magnet or the like and faces the stator core 50a with a gap in the radial direction.

  The upper end opening of the motor frame 30 is closed by the upper bearing bracket 60. The upper bearing bracket 60 is provided with an upper bearing 61 that supports the rotary shaft 4. A motor cover 70 is attached to the upper portion of the motor frame 30 so as to cover the upper bearing bracket 60. An underwater cable 71 is connected to the motor cover 70, and an operation capacitor 72 and the like are accommodated therein.

  The interior of the motor cover 70 communicates with the interior of the motor frame 30 via a communication portion 62 provided on the upper bearing bracket 60. A lead wire (not shown) extending from the stator coil 50 b disposed inside the motor frame 30 is drawn into the motor cover 70 through the communication portion 62 and is electrically connected to the operation capacitor 72 and the underwater cable 71. ing.

FIG. 2 is an arrow AA diagram shown in FIG.
As shown in FIG. 2, an annular gap AG is formed between the outer peripheral portion 103 of the impeller 10 and the opposing portion 15 of the pump casing 11 that faces the outer peripheral portion 103. By forming the annular gap AG narrow, it is possible to obtain a high-lift or long-distance transfer function of the pumped liquid as a high-lift pump. However, if the annular gap AG is narrowly formed, foreign matter (such as fine sand) can be easily caught.

  Moreover, the center of the impeller 10 and the center of the pump casing 11 may be shifted due to the influence of component accuracy, and the gaps L1 and L2 between the impeller 10 and the pump casing 11 may not be uniform. For example, when the center of the impeller 10 deviates from the axis AL to the right side in FIG. 2, the gap dimension L2 becomes smaller than the gap dimension L1.

In such a state, in the portion of the gap dimension L2, the annular gap AG becomes wedge-like narrow, so that foreign matter is easily caught. In addition, since the gap dimension L1 on the opposite side is wider than the gap dimension L2, the foreign matter is likely to enter, and the entered foreign substance moves toward the gap dimension L2 as the impeller 10 rotates and bites. There is a risk of it.
In order to suppress the biting of such foreign matter, the centrifugal pump 1 has a structure shown in FIG.

FIG. 3 is an enlarged cross-sectional view of a main part of the centrifugal pump 1 according to one embodiment.
As shown in FIG. 3, a chamfered portion 104 is formed on the outer peripheral portion 103 of the impeller 10. The chamfered portion 104 may be an inclined surface formed by so-called C chamfering, and is formed on the back surface 10 b side of the outer peripheral portion 103 of the impeller 10. The inclination angle of the chamfered portion 104 is approximately −45 degrees with respect to the back surface 10 b of the impeller 10, and the obtuse angle portion θ <b> 1 of approximately 135 degrees is formed on the outer peripheral portion 103.

  On the other hand, a chamfered portion 151 is also formed in the facing portion 15 of the pump casing 11. The chamfered portion 151 may also be an inclined surface formed by so-called C chamfering, and is formed on the surface 10 a side of the outer peripheral portion 103 of the impeller 10. The angle of inclination of the chamfered portion 151 is approximately −45 degrees with respect to the back surface 10 b of the impeller 10 like the chamfered portion 104, and the obtuse angle portion θ <b> 2 of approximately 135 degrees is formed in the facing portion 15. The chamfered portions 104 and 151 and the obtuse angle portions θ1 and θ2 do not have to be the same angle.

  A chamfered portion 104 formed on the impeller 10 is formed in an upper half region (on the back surface 10b side) in the axial direction of the outer peripheral portion 103 (note that a horizontal line indicated by reference character B in FIG. Passing through the axial middle position). On the other hand, the chamfered portion 151 formed in the pump casing 11 is formed in a lower region (on the surface 10a side) from the lower end (horizontal line B) position of the chamfered portion 104 of the facing portion 15.

  In the annular gap AG formed by the chamfered portions 104 and 151, the gap dimension in the radial direction of the impeller 10 continuously changes from the front surface 10 a side to the back surface 10 b side in the axial direction of the impeller 10. Specifically, the clearance dimension of the annular clearance AG increases continuously after decreasing from the front surface 10a side to the back surface 10b side in the axial direction of the impeller 10 as L2-1 → L2-2 → L2-3. It turns.

  The gap dimension L2-1 is a gap dimension at the lower end position of the chamfer 151. The gap dimension L2-2 is a gap dimension at the upper end position of the chamfered portion 151 (lower end position of the chamfered portion 104). The gap dimension L2-3 is a gap dimension at the upper end position of the chamfered portion 104. The gap dimension of the annular gap AG gradually decreases from L2-1 to L2-2 and gradually increases from L2-2 to L2-3 from the front surface 10a side to the back surface 10b side.

Next, the operation of the centrifugal pump 1 having the above configuration will be described with reference to FIG.
FIG. 4 is an explanatory diagram for explaining the operation of the centrifugal pump 1 according to the embodiment. FIG. 4A shows an enlarged cross-sectional view of a main part of the centrifugal pump 1 including the chamfered portions 104 and 151 described above, and FIG. 4B shows a centrifugal pump 1 ′ that does not include the chamfered portions 104 and 151 as a comparative example. The principal part expanded cross section is shown.

  As shown in FIG. 4B, in the centrifugal pump 1 ′ not provided with the chamfered portions 104 and 151 described above, the outer peripheral portion 103 of the impeller 10, and the opposing portion 15 of the pump casing 11 that faces the outer peripheral portion 103, , A parallel annular gap AG having a gap dimension L2 is formed from the front surface 10a side to the back surface 10b side in the axial direction of the impeller 10. In such an annular gap AG, as described above, when the foreign matter X bites in a wedge shape, the foreign matter X does not come off naturally, and the centrifugal pump 1 needs to be disassembled.

  On the other hand, as shown in FIG. 4A, in the centrifugal pump 1 including the chamfered portions 104 and 151, the outer peripheral portion 103 of the impeller 10, the opposing portion 15 of the pump casing 11 facing the outer peripheral portion 103, In the meantime, an annular gap AG in which the gap dimension in the radial direction of the impeller 10 continuously changes is formed from the front surface 10 a side to the back surface 10 b side in the axial direction of the impeller 10. In such an annular gap AG, there is no parallel part as shown in FIG. 4B, so that the foreign matter X is difficult to bite. Further, since such an annular gap AG gradually spreads toward the front surface 10a side and the rear surface 10b side of the impeller 10, the foreign matter X is easily discharged to the front surface 10a side or the rear surface 10b side.

  Further, since the chamfered portion 104 is formed on the back surface 10b side of the outer peripheral portion 103 of the impeller 10, it is possible to suppress the biting of the foreign matter X that has entered the back surface 10b side of the impeller 10. Further, since the obtuse angle portion θ1 is formed on the outer peripheral portion 103 of the impeller 10 in which the chamfered portion 104 is formed, for example, the chamfered portion 104 is formed from the rear surface 10b to the front surface 10a of the impeller 10 and the outer peripheral portion 103 is formed. Since the strength is higher than the case where an acute angle portion is formed on the outer peripheral portion of the impeller 10 and the corner drop or scraping at the outer peripheral portion 103 of the impeller 10 can be suppressed, the annular gap AG can be narrowed, and the height of the pumped liquid as a high head pump Alternatively, the long distance transfer function is not impaired.

  Further, since the chamfered portion 151 is formed on the surface 10a side of the facing portion 15 of the pump casing 11, the chamfering of the foreign matter X on the surface 10a side (the suction port 13 side) of the impeller 10 can be suppressed. In addition, since the obtuse angle portion θ2 is formed in the facing portion 15 of the pump casing 11 in which the chamfered portion 151 is formed, similarly, a corner drop or scraping in the facing portion 15 can be suppressed.

  Thus, according to the above-described embodiment, the centrifugal pump 1 includes the impeller 10 that rotates around the predetermined axis and the pump casing 11 that houses the impeller 10, and the outer peripheral portion of the impeller 10. An annular gap AG is formed between the outer peripheral portion 103 and the facing portion 15 of the pump casing 11 facing the outer peripheral portion 103, and the annular gap AG extends from the front surface 10 a side to the rear surface 10 b side in the axial direction of the impeller 10. By adopting a configuration in which the gap size in the radial direction of the impeller 10 is continuously reduced and then increased, without impairing the height or long-distance transfer function of the liquid as a high head pump, Biting of the foreign matter X can be suppressed.

  Although preferred embodiments of the present invention have been described and described above, it should be understood that these are exemplary of the present invention and should not be considered as limiting. Additions, omissions, substitutions, and other changes can be made without departing from the scope of the invention. Accordingly, the invention is not to be seen as limited by the foregoing description, but is limited by the scope of the claims.

  For example, in the present invention, it is only necessary to eliminate a portion parallel to the annular gap AG. Therefore, the modification examples shown in FIGS. In the following description, the same or equivalent components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof is simplified or omitted.

  For example, like the centrifugal pump 1A shown in FIG. 5, curved chamfered portions 104A and 151A formed by so-called R chamfering may be provided. In this case as well, it can be considered that the obtuse angle portions θ1 and θ2 described above are formed in the outer peripheral portion 103 and the facing portion 15. That is, when the chamfered portion 104A is formed, the curved surface of the chamfered portion 104 intersects the back surface 10b and the outer peripheral portion 103 in the cross-sectional view shown in FIG. When the intersection point with the back surface 10b is the intersection point P1, the intersection point with the outer peripheral portion 103 is the intersection point P2, and the intersection point P1 and the intersection point P2 are connected by a straight line, the straight line and the outer peripheral portion 103 intersect at an obtuse angle (θ1). The portion that intersects at this obtuse angle exhibits the effect equivalent to the obtuse angle portion θ1 described above, and can therefore be regarded as the obtuse angle portion θ1. That is, even if it is R chamfering, it can be considered that the obtuse angle part θ1 similar to C chamfering is formed in the C chamfering process. Can be obtained. In addition, it can be considered that the obtuse angle part θ2 is formed by defining the intersection points P3 and P4 in the same manner on the facing part 15 side.

  Further, for example, chamfered portions 104B1 and 104B2 may be provided only on the outer peripheral portion 103 of the impeller 10 as in the centrifugal pump 1B illustrated in FIG. Note that the chamfered portions 104B1 and 104B2 may be formed in a curved shape by R chamfering as in FIG.

  Further, for example, as in the centrifugal pump 1C shown in FIG. 6B, only the facing portion 15 of the pump casing 11 may be provided with chamfered portions 151C1 and 151C2. Note that the chamfered portions 151C1 and 151C2 may also be formed in a curved shape by R chamfering as in FIG.

Further, for example, a chamfered portion 104D may be provided only on the outer peripheral portion 103 of the impeller 10 as in the centrifugal pump 1D shown in FIG. Note that the chamfered portion 104D may also be formed into a curved surface by R chamfering as in FIG. In this case, the gap dimension of the annular gap AG continuously decreases from the front surface 10a side to the back surface 10b side of the impeller 10.
Further, the chamfered portion 104D may be formed on the back surface 10b side (in a reverse inclination), and the gap size of the annular gap AG may be continuously increased from the front surface 10a side to the back surface 10b side of the impeller 10.

  DESCRIPTION OF SYMBOLS 1 ... Centrifugal pump, 10 ... Impeller, 10a ... Front surface, 10b ... Back surface, 11 ... Pump casing, 15 ... Opposite part, 103 ... Outer peripheral part, 104 ... Chamfered part, 151 ... Chamfered part, AG ... Annular gap, AL ... Axis, B ... Horizontal line, L1 ... Gap size, L2 ... Gap size, L2-1 ... Gap size, L2-2 ... Gap size, L2-3 ... Gap size, X ... Foreign matter, θ1 ... Oblique angle part, θ2 ... Oblique angle part

Claims (6)

A centrifugal pump having an impeller that rotates about a predetermined axis, and a pump casing that houses the impeller,
An annular gap is formed between the outer peripheral portion of the impeller and the opposing portion of the pump casing that faces the outer peripheral portion,
The annular gap is characterized in that the gap dimension in the radial direction of the impeller continuously decreases, increases, or increases after decreasing from the front side to the back side in the axial direction of the impeller. Centrifugal pump.   2. The centrifugal pump according to claim 1, wherein a chamfered portion that forms the annular gap is formed on at least one of an outer peripheral portion of the impeller and a facing portion of the pump casing.   The centrifugal pump according to claim 2, wherein the chamfered portion is formed on at least one of the front surface side and the back surface side of the outer peripheral portion of the impeller.   4. The centrifugal pump according to claim 2, wherein the chamfered portion is formed on at least one of the front surface side and the back surface side of the facing portion of the pump casing.   The chamfered portion is on one side of the outer peripheral portion of the impeller, either the front surface side or the back surface side, and on the other side different from the one side among the front surface side and the back surface side of the opposed portion of the pump casing. It forms, The centrifugal pump as described in any one of Claims 2-4 characterized by the above-mentioned.   6. The centrifugal pump according to claim 5, wherein an obtuse angle portion is formed at an outer peripheral portion of the impeller in which the chamfered portion is formed and an opposing portion of the pump casing.

Images